Nanocomposite Packaging Film

ABSTRACT

A multi-layered nanocomposite film for use in packaging is provided. More particularly, the film contains at least one core layer positioned adjacent to at least one outer layer. For example, in one embodiment, the film contains a core layer that is positioned between two outer layers. The core layer(s) and/or outer layer(s) may be formed from a polymer composition that contains an ethylene polymer, nanoclay having an organic surface treatment, and a compatibilizer that includes an olefin component and a polar component.

RELATED APPLICATION

The present application claims priority to U.S. Patent Application Ser.No. 61/934,463 filed on Jan. 31, 2014, which is incorporated herein inits entirety by reference thereto,

BACKGROUND OF THE INVENTION

Packaging films are often formed from olefinic polymers, such aspolyethylene. In recent years, however, petroleum resources have becomemore expensive and manufacturers and consumers alike have become moreaware of the sustainability need for packaging films with a smallercarbon footprint, which means reduced carbon emissions during the entirelife cycle of the manufacture of packaging films. While attempts havebeen made to add various additives, such as renewable polymers, to filmsto reduce the content of petroleum-derived olefinic polymers, thisusually results in a corresponding decrease in some mechanicalproperties (e.g., ductility) or tensile strength, etc.), which is highlyundesirable for the manufacturers and users of packaging materials. Assuch, a need currently exists for a film that has a better environmentalimpact as indicated by reduced carbon footprint or reduced consumptionof petroleum-based polymers, but yet can also exhibit good mechanicalproperties required for high-performance packaging film applications.

SUMMARY OF THE INVENTION:

In accordance with one embodiment of the present invention, a packagingfilm is disclosed that has a thickness of about 50 micrometers or less.The film contains a core layer that is positioned adjacent to an outerlayer, wherein the core layer, the outer layer, or both are formed froma polymer composition. The polymer composition contains from about 70wt. % to about 99 wt. % of an ethylene polymer, from about 0.1 wt. % toabout 20 wt. % of a nanoclay having an organic surface treatment, andfrom 0.05 wt. % to about 15 wt. % of a polyolefin compatibilizer thatcontains an olefin component and a polar component.

In accordance with another embodiment of the present invention, apackaging film is disclosed that has a thickness of about 50 micrometersor less. The film contains a core layer that is positioned between afirst outer layer and a second outer layer, wherein the core layerconstitutes from about 50 wt. % to about 99 wt. % of the film and theouter layers constitute from about 1 wt. % to about 50 wt. % of thefilm. Further, the core layer, first outer layer, second outer layer, ora combination thereof are formed from a polymer composition. The polymercomposition that contains from about 70 wt. % to about 99 wt. % of anethylene polymer, from about 0.1 wt. % to about 20 wt. % of a nanoclayhaving an organic surface treatment, and from 0.05 wt. % to about 15 wt.% of a polyolefin compatibilizer that contains an olefin component and apolar component.

Other features and aspects of the present invention are described inmore detail below.

BRIEF DESCRIPTION OF THE DRAWING

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth more particularly in the remainder of the specification, whichmakes reference to the appended figure in which:

FIG. 1 is a schematic illustration of one embodiment of a process thatcan be used to form the film of the present invention;

FIG. 2 is an X-ray diffraction graph for Example 5;

FIG. 3 are transmission electron microphotographs of Example 5 in whichFIG. 3(a) is at a lower magnification (depicted scale of 2 μm) and FIG.3(b) is at a higher magnification (depicted scale of 200 nm);

FIG. 4 is a graph that depicts logarithmic storage modulus (G′) vs.logarithmic frequency (γ) for the samples of Example 5;

FIG. 5 is a graph that depicts complex viscosity η* vs. logarithmicfrequency (γ) for the samples of Example 5;

FIG. 6 is a graph that depicts log G′ (storage modulus) and log G″ (lossmodulus) vs. logarithmic frequency (γ) for the samples of Example 5;

FIG. 7 is a perspective view of a testing apparatus that may be used toevaluate noise levels, with the apparatus door open;

FIG. 8 is a perspective view of the testing apparatus of FIG. 7, withthe apparatus door closed; and

FIG. 9 is a plan view of the apparatus of FIG. 7 taken along arrow 190.

Repeat use of reference characters in the present specification anddrawing is intended to represent same or analogous features or elementsof the invention.

DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

Reference now will be made in detail to various embodiments of theinvention, one or more examples of which are set forth below. Eachexample is provided by way of explanation, not limitation of theinvention. In fact, it will be apparent to those skilled in the art thatvarious modifications and variations may be made in the presentinvention without departing from the scope or spirit of the invention.For instance, features illustrated or described as part of oneembodiment, may be used on another embodiment to yield a still furtherembodiment. Thus, it is intended that the present invention cover suchmodifications and variations.

Generally speaking, the present invention is directed to a multi-layerednanocomposite film for use in packaging. More particularly, the filmcontains at least one core layer positioned adjacent to at least oneouter layer. For example, in one embodiment, the film contains a corelayer that is positioned between two outer layers. In accordance withthe present invention, the core layer(s) and/or outer layer(s) may beformed from a polymer composition that contains an ethylene polymer,nanoclay having an organic surface treatment, and a compatibilizer thatincludes an olefin component and a polar component. Nanoclays, forexample, typically constitute from about 0.1 wt. % to about 20 wt. %, insome embodiments from about 0.5 wt. % to about 15 wt. %, and in someembodiments, from about 1 wt. % to about 10 wt. % of the polymercomposition. Ethylene polymers may likewise constitute from about 70 wt.% to about 99 wt. %, in some embodiments from about 75 wt. % to about 98wt. %, and in some embodiments, from about 80 wt. % to 95 wt. % of thepolymer composition. Compatibilizers may also constitute from about 0.05wt. % to about 15 wt. %, in some embodiments from about 0.1 wt. % toabout 12 wt. %, and in some embodiments, from about 0.2 wt. % to about10 wt. % of the polymer composition.

Due to the use of nanoclay in the polymer composition, the resultingfilm has a better environmental impact as it uses a reduced amount ofethylene polymers. For example, the film has a smaller carbon footprintand can potentially reduce energy input and greenhouse gas emissions.Notably, the present inventors have discovered that the film can achievesuch an improved environmental impact without a sacrifice in mechanicalproperties. In fact, in many cases, it was surprisingly found thatcertain mechanical properties (e.g., peak stress, modulus, etc.) weresignificantly increased even when the polymer usage was substantiallyreduced. These benefits are accomplished, in part, by selectivelycontrolling the particular type and concentration of the components usedto form the film, as well as the manner in which it is formed. Forexample, without intending to be limited by theory, it is believed thatthe organic surface treatment can have a plastifying-like effect on thenanoclay, which can reduce the degree of surface friction between thenanoclay and domains of the ethylene polymer when the composition issubjected to an elongational force. It is also believed that the surfacetreatment can have a lubricating effect, which allows the macromolecularchains of the ethylene polymer to slip along the nanoclay surfacewithout causing debonding, thus maintaining a high degree of ductility.This can be accomplished by selectively controlling the particular typeof surface treatment, the type of ethylene polymer, and the degree ofmixing during melt extrusion. Furthermore, the nanoclay can optionallybe pre-blended with the ethylene polymer and compatibilizer to form thepolymer composition, which is thereafter passed through an extrusion dieand formed into a film. Through such a multi-step formation process, thenanoclay can become well-dispersed and more uniformly oriented, therebyeven further enhancing ductility. It is believed that certain types offormation processes (e.g., cast film or blown film processes) are alsoparticularly well suited to allow the formation of unique structureswith a high degree of ductility.

One parameter that is indicative of good ductility is the peakelongation of the film in the machine direction (“MD”) and/orcross-machine direction (“CD”). For example, the film typically exhibitsa peak elongation in the machine direction of about 400% or more, insome embodiments about 500% or more, in some embodiments about 550% ormore, and in some embodiments, from about 600% to about 2000%. The filmmay likewise exhibit a peak elongation in the cross-machine direction ofabout 750% or more, in some embodiments about 800% or more, in someembodiments about 800% or more, and in some embodiments, from about 850%to about 2500%. Despite having such good ductility, the film of thepresent invention is nevertheless able to retain good mechanicalstrength. For example, the film of the present invention may exhibit anultimate tensile strength in the machine direction and/or cross-machinedirection of from about 20 to about 150 Megapascals (MPa), in someembodiments from about 25 to about 100 MPa, and in some embodiments,from about 30 to about 80 MPa. The Young's modulus of elasticity of thefilm, which is equal to the ratio of the tensile stress to the tensilestrain and is determined from the slope of a stress-strain curve, mayalso be good. For example, the film typically exhibits a Young's modulusin the machine direction and/or cross-machine direction of from about 50to about 500 MPa, in some embodiments from about 100 to about 400 MPa,and in some embodiments, from about 150 to about 350 MPa.

Surprisingly, the good ductility and other mechanical properties can beachieved even though the film has a very low thickness. In this regard,the normalized mechanical properties, which are determined by dividing aparticular mechanical value (e.g., Young's modulus, tensile strength, orpeak elongation) by the average film thickness (μm), may also beimproved. For example, the film may exhibit a normalized peak elongationin the machine direction of about 15%/μm or more, in some embodimentsabout 20%/μm or more, and in some embodiments, from about 25%/μm toabout 60%/μm. The film may likewise exhibit a normalized peak elongationin the cross-machine direction of about 40%/μm or more, in someembodiments about 50%/μm or more, and in some embodiments, from about55%/μm to about 80%/μm. The film may exhibit a normalized ultimatetensile strength in the machine direction and/or cross-machine directionof from about 0.5 to about 20 MPa/μm, in some embodiments from about 1to about 12 MPa/μm, and in some embodiments, from about 2 to about 8MPa/μm. The normalized Young's modulus in the machine direction and/orcross-machine direction may also be from about 5 to about 50 MPa/μm, insome embodiments from about 10 to about 40 MPa/μm, and in someembodiments, from about 15 to about 35 MPa/μm. The actual thickness ofthe film is typically about 50 micrometers or less, in some embodimentsfrom about 1 to about 40 micrometers, in some embodiments from about 5to about 35 micrometers, and in some embodiments, from about 10 to about30 micrometers.

The present inventors have also discovered that the film may generate arelatively low degree of noise when physically deformed. When subjectedto physical deformation for two (2) minutes, for instance, the noiselevel of the film may be about 45 decibels (dB) or less, in someembodiments about 42 dB or less, and in some embodiments, from about 20dB to about 40 dB, such as determined at a frequency of 2,000 Hz or4,000 Hz. The “normalized noise level” of the film, which is determinedby dividing the noise level of the film that is generated while the filmis subjected to physical deformation for two (2) minutes by the noiselevel generated by an ambient environment, may likewise be about 2.5 orless, in some embodiments about 2.4 or less, and in some embodiments,from about 1.5 to about 2.3, such as determined at a frequency of 2,000Hz or 4,000 Hz. In addition to a reduced noise level, the film of thepresent invention may also have excellent barrier properties to oxygentransmission. Without intending to be limited by theory, it is believedthat the nanoclay platelet structure can create a tortuous pathway inthe film, which may slow down the transmission rate and reduce theamount of permeant oxygen. For example, the oxygen transmission rate maybe about 350 cm³/100 in²*24-hours or less, in some embodiments about 330cm³/100 in²*24-hours or less, and in some embodiments, from about 100 toabout 300 cm³/100 in²*24-hours, such as determined in accordance withASTM 03985-05 at a temperature of 23° C. and a relative humidity of 0%.

Various embodiments of the present invention will now be described inmore detail.

I. Polymer Composition

A. Ethylene Polymer

Any of a variety of ethylene polymers may generally be employed in thepresent invention. In one embodiment, for instance, the ethylene polymermay be a copolymer of ethylene and an α-olefin, such as a C₃-C₂₀α-olefin or C₃-C₁₂ α-olefin. Suitable α-olefins may be linear orbranched (e.g., one or more C₁-C₃ alkyl branches, or an aryl group).Specific examples include 1-butene; 3-methyl-1-butene;3,3-dimethyl-1-butene; 1-pentene; t-pentene with one or more methyl,ethyl or propyl substituents; 1-hexene with one or more methyl, ethyl orpropyl substituents; 1-heptene with one or more methyl, ethyl or propylsubstituents; 1-octene with one or more methyl, ethyl or propylsubstituents; 1-nonene with one or more methyl, ethyl or propylsubstituents; ethyl, methyl or dimethyl-substituted 1-decene;1-dodecene; and styrene. Particularly desired α-olefin comonomers are1-butene, 1-hexene and 1-octene. The ethylene content of such copolymersmay be from about 60 mole % to about 99 mole %, in some embodiments fromabout 80 mole % to about 98.5 mole %, and in some embodiments, fromabout 87 mole % to about 97.5 mole %. The α-olefin content may likewiserange from about 1 mole % to about 40 mole %, in some embodiments fromabout 1.5 mole % to about 15 mole %, and in some embodiments, from about2.5 mole % to about 13 mole %. The density of the polyethylene may varydepending on the type of polymer employed, but generally ranges fromabout 0.85 to about 0.96 grams per cubic centimeter (g/cm³).Polyethylene “plastomers”, for instance, may have a density in the rangeof from about 0.85 to about 0.91 g/cm³. Likewise, “linear low densitypolyethylene” (LLDPE) may have a density in the range of from about 0.91to about 0.940 g/cm³; “low density polyethylene” (LDPE) may have adensity in the range of from about 0.910 to about 0.940 g/cm³; and “highdensity polyethylene” (HDPE) may have density in the range of from about0.940 to about 0.960 g/cm³, such as determined in accordance with ASTM0792.

In certain embodiments, an ethylene polymer may be employed that has arelatively low density in the range of about 0.94 g/cm³ or less, in someembodiments from about 0.85 to about 0.94 g/cm³, and in someembodiments, from about 0.90 to about 0.935 g/cm³. One or more polymersmay be employed in the composition that has these densitycharacteristics. Linear low density polyethylene (“LLDPE”) and/or lowdensity polyethylene (“LDPE”) are particularly suitable. The low densityethylene polymer may have a relatively low melting temperature andmodulus of elasticity, which can provide the resulting film with arelatively soft and ductile feel: For example, the low density ethylenepolymer may have a melting temperature of from about 50° C. to about145° C., in some embodiments from about 75° C. to about 140° C., and insome embodiments, from about 100° C. to about 135° C., and a modulus ofelasticity of from about 50 to about 700 MPa, in some embodiments fromabout 75 to about 600 MPa, and in some embodiments, from about 100 toabout 500 MPa, as determined in accordance with ASTM D638-10. The lowdensity ethylene polymer may also have a melt flow index of from about0.1 to about 100 grams per 10 minutes, in some embodiments from about0.5 to about 50 grams per 10 minutes, and in some embodiments, fromabout 1 to about 40 grams per 10 minutes, determined at a load of 2160grams and at 190° C., as determined in accordance with ASTM D1238-13 (orISO 1133),

If desired, low density ethylene polymers may constitute a substantialmajority of the polymers employed in the composition. For example, lowdensity ethylene polymers may constitute about 80 wt. % or more, in someembodiments about 85 wt. % or more, and in some embodiments, from about90 wt. % to 100 wt. % of the polymers employed in the composition. Ofcourse, in other embodiments, high density ethylene polymers may also beemployed. For example, low density ethylene polymers may constitute fromabout 5 wt. % to about 90 wt. %, in some embodiments from about 10 wt. %to about 80 wt. %, and in some embodiments, from about 20 wt. % to 70wt. % of the polymer composition and high density ethylene polymers mayconstitute from about 5 wt. % to about 90 wt. %, in some embodimentsfrom about 10 wt. % to about 80 wt. %, and in some embodiments, fromabout 20 wt. % to 70 wt. % of the polymer composition. The high densityethylene polymers typically have a density of greater than about 0.94g/cm³, in some embodiments from about 0.945 to about 0.98 g/cm³, and insome embodiments, from about 0.95 to about 0.97 g/cm³. Once again, oneor more polymers may be employed in the composition that has thesecharacteristics. High density polyethylene (“HDPE”) is particularlysuitable. The high density ethylene polymers may have a relatively lowmelting temperature and high modulus of elasticity. For example, thehigh density ethylene polymers may have a melting temperature of fromabout 70° C. to about 160° C., in some embodiments from about 85° C. toabout 150° C., and in some embodiments, from about 110° C. to about 145°C., and a modulus of elasticity of from about 700 to about 5,000 MPa, insome embodiments from about 750 to about 3,000 MPa, and in someembodiments, from about 1,000 to about 2,000 MPa, as determined inaccordance with ASTM D638-10. The high density ethylene polymers mayalso have a melt flow index of from about 0.1 to about 100 grams per 10minutes, in some embodiments from about 0.5 to about 50 grams per 10minutes, and in some embodiments, from about 1 to about 40 grams per 10minutes, determined at a load of 2160 grams and at 190° C., asdetermined in accordance with ASTM D1238-13 (or ISO 1133),

Various known techniques may generally be employed to form ethylenepolymers. For instance, ethylene polymers may be formed using a freeradical or a coordination catalyst (e.g., Ziegler-Natta). Typically, theethylene polymer is formed from multi-site Ziegler-Natta catalysts, theresulting ethylene polymer has a broad molecular weight distributionwith a polydispersity index (weight average molecular weight divided bynumber average molecular weight) of up to 20 or higher. The ethylenepolymer made by a single-site coordination catalyst, such as ametallocene catalyst, has a narrow molecular weight distribution. Such acatalyst system produces ethylene polymers in which a comonomer israndomly distributed within a molecular chain and uniformly distributedacross the different molecular weight fractions. Metallocene-catalyzedpolyolefins are described, for instance, in U.S. Pat. No. 5,571,619 toMcAlpin et al.; U.S. Pat. No. 5.322,728 to Davis et U.S. Pat. No.5,472,775 to Obijeski et al.; U.S. Pat. No. 5,272,236 to Lai et al.; andU.S. Pat. No. 6,090,325 to Wheat, et al. Examples of metallocenecatalysts include bis(n-butylcyclopentadienyl)titanium dichloride,bis(n-butylcyclopentadienyl)zirconium dichloride,bis(cyclopentadienyl)scandium chloride, bis(indenyl)zirconiumdichloride, bis(methylcyclopentadienyl)titanium dichloride,bis(methylcyclopentadienyl)zirconium dichloride, cobaltocene,cyclopentadienyltitanium trichloride, ferrocene, hafnocene dichloride,isopropyl(cyclopentadienyl,-1-flourenyl)zirconium dichloride,molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene,titanocene dichloride, zirconocene chloride hydride, zirconocenedichloride, and so forth. Polymers made using metallocene catalyststypically have a narrow molecular weight range. For instance,metallocene-catalyzed polymers may have polydispersity numbers(M_(w)/M_(n)) of below 4, controlled short chain branching distribution,and controlled isotacticity. Ethylene polymers may also have amono-modal or a multimodal (e.g., bimodal) molecular weightdistribution, such as measured using gel permeation chromatography).

B. Nanoclay

The term “nanoclay” generally refers to nanoparticles of a clay material(a naturally occurring mineral, an organically modified mineral, or asynthetic nanomaterial). The clay material typically has a flake-likemorphology in that it possesses a relatively flat or platelet shape. Theclay platelets may, for example, have an average thickness of from about0.2 to about 100 nanometers, in some embodiments from about 0.5 to about50 nanometers, and in some embodiments, from about 1 to about 20nanometers. The “aspect ratio” of the clay material (i.e., the averagelength of the platelets divided by the average thickness) is alsorelatively large, such as from about 20 to about 1000, in someembodiments from about 50 to about 80, in some embodiments, from about100 to about 400. The average length (e.g., diameter) may, for instance,range from about 20 nanometers to about 10 micrometers, in someembodiments from about 100 nanometers to about 5 micrometers, and insome embodiments, from about 200 nanometers to about 4 micrometers.

The clay material may be formed from a phyllosilicate, such as asmectite clay mineral (e.g., bentonite, kaolinite, or montmorillonite,as well as salts thereof, such as sodium montmorillonite, magnesiummontmorillonite, calcium montmorillonite, etc.); nontronite; beidellite;volkonskoite; hectorite; saponite; sauconite; sobockite; stevensite;svinfordite; vermiculite; etc. Other useful nanoclays include micaceousminerals (e.g., illite) and mixed illite/smectite minerals, such asrectorite, tarosovite, ledikite and admixtures of illites with the clayminerals named above. Particularly suitable are montmorillonite (2:1layered smectite clay structure), bentonite (aluminium phyllosilicateformed primarily of montmorillonite), kaolinite (1:1 aluminosilicatehaving a platy structure and empirical formula of Al₂Si₂O₅(OH)₄),halloysite (1:1 aluminosilicate having a tubular structure and empiricalformula of Al2Si₂O₅(OH)₄), etc.

As noted above, the nanoclay also contains an organic surface treatmentthat enhances the hydrophobicity of the clay material and thus improvesits compatibility with the ethylene polymer. In one embodiment, theorganic surface treatment may be formed from a quaternary onium (e.g.,salt or ion), which may become intercalated via ion-exchange into theinterlayer spaces between adjacent layered clay platelets. Thequaternary onium ion may have the following structure:

wherein

X is N, P, S, or O; and

R₁, R₂, R₃ and R₄ are independently hydrogen or organic moieties, suchas linear or branched alkyl, aryl or aralkyl moieties having 1 to about24 carbon atoms.

Particularly suitable quaternary ammonium ions are those having thestructure below:

wherein

R₁ is a long chain alkyl moiety ranging from C₆ to C₂₄, straight orbranched chain, including mixtures of long chain moieties, such as C₆,C₈, C₁₀, C₁₂, C₁₄, C₁₆, C₁₈, C₂₀, C₂₂ and C₂₄, alone or in anycombination; and

R₂, R₃ and R₄ are moieties, which may be the same or different, selectedfrom the group consisting of H, alkyl, hydroxyalkyl, benzyl, substitutedbenzyl, e.g., straight or branched chain alkyl-substituted andhalogen-substituted; ethoxylated or propoxylated alkyl; ethoxylated orpropoxylated benzyl (e.g., 1-10 moles of ethoxylation or 1-10 moles ofpropoxylation).

Additional useful multi-charged spacing/coupling agents include forexample, tetra-, tri-, and di-onium species such as tetra-ammonium,tri-ammonium, and di-ammonium (primary, secondary, tertiary, andquaternary), -phosphonium, -oxonium, or -sulfonium derivatives ofaliphatic, aromatic or arylaliphatic amines, phosphines, esters,alcohols and sulfides. Illustrative of such materials are di-oniumcompounds of the formula:

R¹—X⁺—R—Y⁺

where X^(+ and Y) ⁺, are the same or different, and are ammonium,sulfonium, phosphonium, or oxonium radicals such as —NH(CH₃)₂ ⁺,—NH₂(CH₃)⁺, —N(CH₃)₃ ⁺, —N(CH₃)₂(CH₂CH₃)⁺, —N(CH₃)(CH₂CH₃)₂ ⁺, —S(CH₃)₂⁺, —S(CH₃)₂ ⁺, —P(CH₃)₃ ⁺, —NH₃ ⁺, etc.;

R is an organic spacing, backbone radical, straight or branched, such asthose having from 2 to 24 carbon atoms, and in some embodiments from 3to 10 carbon atoms, in a backbone organic spacing molecule covalentlybonded at its ends to charged N⁺, P⁺, S⁺ and/or O⁺ cations;

R¹ can be hydrogen, or a linear or branched alkyl radical of 1 to 22carbon atoms, linear or branched, and in some embodiments, 6 to 22carbon atoms,

Illustrative of useful R groups are alkyls (e.g., methyl, ethyl, butyl,octyl, etc.); aryl (e.g., benzyl, phenylalkyl, etc.); alkylenes (e.g.,methylene, ethylene, octylene, nonylene, tert-butylene, neopentylene,isopropylene, sec-butylene, dodecylene, etc.); alkenylenes (e.g.,1-propenylene, 1-butenylene, 1-pentenylene, 1-hexenylene, 1-heptenylene,1-octenylene, etc.); cycloalkenylenes (e.g., cyclohexenylene,cyclopentenylene, etc.); hydroxyalkyl (e.g. hydroxymethyl, hydroxyethyl,hydroxyl-n-propyl, hydroxyisopropyl, hydroxyl-n-butyl,hydroxyl-iso-butyl, hydroxyl-tert-butyl, etc.), alkanoylalkylenes (e.g.,butanoyl octadecylene, pentanoyl nonadecylene, octanoyl pentadecylene,ethanoyl undecylene, propanoyl hexadecylene, etc.); alkylaminoalkylenes(e.g., methylamino octadecylene, ethylamino pentadecylene, butylaminononadecylene, etc.); dialkylaminoalkylene (e.g., dimethylaminooctadecylene, methylethylamino nonadecylene, etc.); arylaminoalkylenes(e.g., phenylamino octadecylene, p-methylphenylamino nonadecylene,etc.); diarylaminoalkylenes (e.g., diphenylamino pentadecylene,p-nitrophenyl-p′-methylphenylamino octadecylene, etc.);alkylarylaminoalkylenes (e.g., 2-phenyl-4-methylamino pentadecylene,etc.); alkylsulfinylenes, alkylsulfonylenes, alkylthio, arylthio,arylsulfinylenes, and arylsulfonylenes (e.g., butylthio octadecylene,neopentylthio pentadecylene, methylsulfinylnonadecylene, benzylsulfinylpentadecylene, phenylsulfinyl octadecylene, propylthiooctadecylene,octylthio pentadecylene, nonylsulfonyl nonadecylene, octylsulfonylhexadecylene, methylthio nonadecylene, isopropylthio octadecylene,phenylsulfonyl pentadecylene, methylsulfonyl nonadecylene, nonylthiopentadecylene, phenylthio octadecylene, ethyltio nonadecylene,benzylthio undecylene, phenethylthio pentadecylene, sec-butylthiooctadecylene, naphthylthio undecylene, etc.); alkoxycarbonylalkylenes(e.g., methoxycarbonylene, ethoxycarbonylene, butoxycarbonylene, etc.);cycloalkylenes (e.g., cyclohexylene, cyclopentylene, cyclooctylene,cycloheptylene, etc.); alkoxyalkylenes (e.g., methoxymethylene,ethoxymethylene, butoxymethylene, propoxyethylene, pentoxybutylene,etc.); aryloxyalkylenes and aryloxyarylenes (e.g., phenoxyphenylene,phenoxymethylene, etc.); aryloryalkylenes (e.g., phenoxydecylene,phenoxyoctylene, etc.); alylalkylenes (e,g., benzylene, phenthylene,8-phenyloctylene, 10-phenyldecylene, etc.); alkylarylenes (e.g.,3-decylphenylene, 4-octylphenylene, 4-nonylphenylene, etc.); andpolypropylene glycol and polyethylene glycol substituents (e.g.,ethylene, propylene, butylene, phenylene, benzylene, tolylene,p-styrylene, p-phenylmethylene, octylene, dodecylene, octadecylene,methoxyethylene, etc.), as well as combinations thereof. Such tetra-,tri-, and di-ammonium, -sulfonium, -phosphonium, -oxonium;ammonium/sulfonium; ammonium/phosphonium; ammonium/oxonium;phosphonium/oxonium; sulfonium/oxonium; and sulfonium/phosphoniumradicals are well known in the art and can be derived from thecorresponding amines, phosphines, alcohols or ethers, and sulfides.

Particularly suitable multi-charged spacing/coupling agent compounds aremulti-onium on compounds that include at least two primary, secondary,tertiary or quaternary ammonium, phosphonium, sulfonium, and/or oxoniumions having the following general formula:

wherein

R is an alkylene, aralkylene or substituted alkylene charged atomspacing moiety; and

Z₁, Z₂, R₁, R₂, R₃, and R₄ may be the same or different and selectedfrom the group consisting of hydrogen, alkyl, aralkyl, benzyl,substituted benzyl (e.g., e.g., straight or branched chainalkyl-substituted and halogen-substituted); ethoxylated or propoxylatedalkyl; ethoxylated or propoxylated benzyl (e.g., 1-10 moles ofethoxylation or 1-10 moles of propoxylation).

Particularly suitable organic cations may include, for instance,quaternary ammonium compounds, such as dimethyl bis[hydrogenated tallow]ammonium chloride (2M2HT), methyl benzyl bis[hydrogenated tallow]ammonium chloride (MB2HT), methyl tris[hydrogenated tallow alkyl]chloride (M3HT), etc. An example of a suitable nanoclay is Nanomer™1.44P, which is a quaternary ammonium modified montmorillonite nanoclayand commercially available from Nanocor, Inc. Other suitable nanoclayadditives include those available from Southern Clay Products, such asCloisite™ 15A, Cloisite™ 30B, Cloisite™ 93A, and Cloisite™ Na⁺.

The onium ion may be introduced into (sorbed within) the interlayerspaces of the clay material in a number of ways. In one method, forexample, the clay material is slurried in water, and the onium ioncompound is dissolved therein. If necessary, the onium ion compound canbe dissolved first in an organic solvent (e.g., propanol). If desired,the nanoclay may also be intercalated with an oligomer and/or polymerintercalant as is known in the art. For example, an olefin polymer oroligomer (e.g., ethylene polymer) intercalant may be employed. Tointercalate an onium ion and an olefin intercalant between adjacentphyllosilicate platelets and optionally separate (exfoliate) the layeredmaterial into individual platelets, for example, the clay material maybe first contacted with the onium ion and simultaneously or thereaftercontacted with the melted oligomer/polymer intercalant to the onium ionintercalated layered material. This may be accomplished, for instance,by directly compounding the materials in an extruder. Alternatively, theoligomer/polymer can be intercalated by an emulsion process byvigorously mixing with an emulsifier. If desired, a coupling agent(e.g., silane coupling agent) may also be employed to help bond theintercalant with the clay material. For example, the clay material maybe initially treated with a coupling agent followed by ion-exchange ofonium ions between the clay material, prior to or simultaneously withintercalation of the oligomer(s) or polymer(s). It should be understoodthat the oligomer or polymer intercalant(s) can also be intercalatedbetween and complexed to the internal platelet faces by other well-knownmechanisms, such as by dipole/dipole bonding (direct intercalation ofthe oligomer or polymer) as described in U.S. Pat. Nos. 5,880,197 and5,877,248, as well as by acidification with substitution with hydrogen(ion-exchanging the interlayer cations with hydrogen by use of an acidor ion-exchange resin) as described in U.S. Pat. Nos. 5,102,948 and5,853,886:

C. Compatibilizer

The compatibilizer may be a polyolefin containing an olefin componentand a polar component. The olefin component is non-polar and thusgenerally has an affinity for the ethylene polymer. The olefin componentmay generally be formed from any linear or branched α-olefin monomer,oligomer, or polymer (including copolymers) derived from an α-olefinmonomer. In one particular embodiment, for example, the compatibilizerincludes at least one linear or branched α-olefin monomer, such as thosehaving from 2 to 20 carbon atoms and preferably from 2 to 8 carbonatoms. Specific examples include ethylene, propylene, 1-butene;3-methyl-1-butene; 3,3-dimethyl-1-butene; 1-pentene; 1-pentene with oneor more methyl, ethyl or propyl substituents; 1-hexene with one or moremethyl, ethyl or propyl substituents; 1-heptene with one or more methyl,ethyl or propyl substituents; 1-octene with one or more methyl, ethyl orpropyl substituents; 1-nonene with one or more methyl, ethyl or propylsubstituents; ethyl, methyl or dimethyl-substituted 1-decene;1-dodecene; and styrene. Particularly desired α-olefin co-monomers areethylene and propylene.

The polyolefin compatibilizer is also functionalized with a polarcomponent, which can be grafted onto the polymer, incorporated as amonomeric constituent of the polymer (e.g., block or random copolymers),etc. When grafted onto a polymer backbone, particularly suitable polargroups are maleic anhydride, maleic acid, acrylic acid, methacrylicacid, fumaric acid, maleimide, maleic acid hydrazide, a reaction productof maleic anhydride and diamine, methylnadic anhydride, dichloromaleicanhydride, maleic acid amide, etc. Maleic anhydride modified polyolefinsare particularly suitable for use in the present invention. Suchmodified polyolefins are typically formed by grafting maleic anhydrideonto a polymeric backbone material. Such maleated polyolefins areavailable from E. I. du Pont de Nemours and Company under thedesignation FUSABOND®, such as the P Series (chemically modifiedpolypropylene), E Series (chemically modified polyethylene), C Series(chemically modified ethylene vinyl acetate), A Series (chemicallymodified ethylene acrylate copolymers or terpolymers), M Series(chemically modified polyethylene), or N Series (chemically modifiedethylene-propylene, ethylene-propylene diene monomer (“EPDM”) orethylene-octene). Alternatively, modifier polyolefins are also availablefrom Chemtura Corp, under the designation POLYBOND® (e.g., acrylicacid-modified polypropylene) and Eastman Chemical Company under thedesignation Eastman G series.

As noted above, the polar component may also be incorporated into thepolyolefin compatibilizer as a monomer. For example, a (meth)acrylicmonomeric component may be employed in certain embodiments. As usedherein, the term “(meth)acrylic” includes acrylic and methacrylicmonomers, as well, as salts or esters thereof, such as acrylate andmethacrylate monomers. Examples of such (meth)acrylic monomers mayinclude methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propylacrylate, n-butyl acrylate, s-butyl acrylate, i-butyl acrylate, t-butylacrylate, n-amyl acrylate, i-amyl acrylate, isobornyl acrylate, n-hexylacrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, n-octylacrylate, n-decyl acrylate, methylcyclohexyl acrylate, cyclopentylacrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate,2-hydroxyethyl methacrylate, n-propyl methacrylate, n-butylmethacrylate, i-propyl methacrylate, i-butyl methacrylate, n-amylmethacrylate, n-hexyl methacrylate, i-amyl methacrylate,s-butyl-methacrylate, t-butyl methacrylate, 2-ethylbutyl methacrylate,methylcyclohexyl methacrylate, cinnamyl methacrylate, crotylmethacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate,2-ethoxyethyl methacrylate, isobornyl methacrylate, etc., as well ascombinations thereof. Other types of suitable polar monomers includeester monomers, amide monomers, etc.

D. Other Components

In addition to the components noted above, other additives may also beincorporated into the film of the present invention, such as slipadditives, melt stabilizers, processing stabilizers, heat stabilizers,light stabilizers, antioxidants, heat aging stabilizers, whiteningagents, bonding agents, fillers, etc. Further, hindered phenols arecommonly used as an antioxidant in the production of films. Somesuitable hindered phenols include those available from Ciba SpecialtyChemicals under the trade name “Irganox®”, such as Irganox® 1076, 1010,or E 201. Moreover, bonding agents may also be added to the film tofacilitate bonding of the film to additional materials (e.g., nonwovenwebs). Examples of such bonding agents include hydrogenated hydrocarbonresins. Other suitable bonding agents are described in U.S. Pat. No.4,789,699 to Kieffer et al. and U.S. Pat. No. 5,695,868 to McCormack.

II. Film Construction

The film of the present invention can have any number of layers, such asfrom 2 to 20 layers, and in some embodiments, from 3 to 10 layers.Regardless of the total number, the film generally contains at least onecore layer that is positioned adjacent to at least one outer layer. Inone embodiment, for example, it may be desirable to employ first andsecond outer layers that sandwich the core layer. The core layer(s)typically constitute a substantial portion of the weight of the film,such as from about 50 wt. % to about 99 wt. %, in some embodiments fromabout 55 wt. % to about 90 wt. %, and in some embodiments, from about 60wt. % to about 85 wt. % of the film. The outer layer(s) may likewiseconstitute from about 1 wt. % to about 50 wt. %, in some embodimentsfrom about 10 wt. % to about 45 wt. %, and in some embodiments, fromabout 15 wt. % to about 40 wt. % of the film, Each outer layer may alsohave a thickness of from about 0.1 to about 10 micrometers, in someembodiments from about 0.5 to about 5 micrometers, and in someembodiments, from about 1 to about 2.5 micrometers. Likewise, the corelayer may have a thickness of from about from about 1 to about 40micrometers, in some embodiments from about 2 to about 25 micrometers,and in some embodiments, from about 5 to about 20 micrometers. As notedabove, the total thickness of the film is typically about 50 micrometersor less, in some embodiments from about 1 to about 40 micrometers, insome embodiments from about 5 to about 35 micrometers, and in someembodiments, from about 10 to about 30 micrometers.

The polymer composition of the present invention may be employed in anylayer of the film, including the core layer and/or the outer layer. Inone embodiment, for example, the core layer is formed from the polymercomposition of the present invention and the outer layer(s) are formedfrom the polymer composition or from an additional polymer material.Likewise, in other possible embodiments, one or more of the outer layersare formed from the polymer composition of the present invention and thecore layer is formed from an additional polymer material. When employed,the additional material may include any type of polymer, such aspolyolefins (e.g., polyethylene, polypropylene, etc.), polyesters,polyamides, styrenic copolymers, polyurethanes, polyvinyl acetate,polyvinyl alcohol, etc. When supplied, the nanoclay may itself be in theform of a masterbatch, which may contain nanoclay particles blended witha polymer (e.g., ethylene polymer). Alternatively, the nanoclay may bein the form of a powder containing particles, such as described above.

One benefit of the present invention is that the particular componentsof the polymer composition can be tailored to achieve differentproperties when employed in different layers of the film. For instance,outer layers are often used for heat sealing or printing. In thisregard, when employed in an outer layer, the polymer composition may usea relatively small amount of nanoclays, such as from about 0.1 wt. % toabout 15 wt. %, in some embodiments from about 0.5 wt. % to about 10 wt.%, and in some embodiments, from about 1 wt. % to about 8 wt. % of thepolymer composition. The polymer composition used to form the outerlayer may also contain an ethylene polymer having a relatively lowdensity, such as about 0.94 g/cm³ or less, in some embodiments fromabout 085 to about 0.94 g/cm³, and in some embodiments, from about 0.90to about 0.935 g/cm³. One or more polymers may be employed in thecomposition that has these density characteristics. Linear low densitypolyethylene (“LLDPE”) and/or low density polyethylene (“LDPE”), whichmay optionally be metallocene-catalyzed as described above, areparticularly suitable. Other suitable ethylene polymers may likewiseinclude copolymers, such as ethylene vinyl acetate (“EVA”) or ethyleneacrylic acid (“EAA”). Such ethylene polymers typically have a relativelylow melting temperature and modulus of elasticity, which can enable themto more readily serve as a heat sealing or printable layer of the film.For example, the ethylene polymer may have a melting temperature of fromabout 50° C. to about 145° C., in some embodiments from about 75° C. toabout 140° C., and in some embodiments, from about 100° C. to about 135°C., and a modulus of elasticity of from about 50 to about 700 MPa, insome embodiments from about 75 to about 600 MPa, and in someembodiments, from about 100 to about 500 MPa, as determined inaccordance with ASTM 0638-10. The ethylene polymer may also have a meltflow index of from about 1 to about 100 grams per 10 minutes, in someembodiments from about 5 to about 50 grams per 10 minutes, and in someembodiments, from about 10 to about 40 grams per 10 minutes, determinedat a load of 2160 grams and at 190° C., as determined in accordance withASTM D1238-13 (or ISO 1133).

When employed in a core layer, which is often used to improve thestrength and rigidity of the film, the polymer composition may employ arelatively high amount of nanoclays, such as from about 0.5 wt. % toabout 20 wt. %, in some embodiments from about 1 wt. % to about 15 wt.%, and in some embodiments, from about 2 wt. % to about 10 wt. % of thepolymer composition. The polymer composition may contain an ethylenepolymer, such as LLDPE, LDPE, metallocene LLDPE, metallocene LDPE, EVA,etc., as well as blends of these polymers. The polymer composition mayalso contain an ethylene polymer having a relatively high density, suchas greater than about 0.94 g/cm³, in some embodiments from about 0.945to about 0.98 g/cm³, and in some embodiments, from about 0.95 to about0.97 g/cm³. Once again, one or more polymers may be employed in thecomposition that has these characteristics. High density polyethylene(“HDPE”) is particularly suitable. For example, the amount of HDPE inthe core layer may range from about 1 wt. % to about 95 wt. %, in someembodiments from about from about 5% to about 90 wt. %, and in someembodiments, from about 10 wt. % to about 85 wt. %. Such high densityethylene polymers typically have a relatively high melting temperatureand modulus of elasticity, which can enable them to more readily serveas a strength enhancing layer of the film. For example, the ethylenepolymer may have a melting temperature of from about 70° C. to about160° C., in some embodiments from about 85° C. to about 150° C., and insome embodiments, from about 110° C. to about 145° C., and a modulus ofelasticity of from about 700 to about 5,000 MPa, in some embodimentsfrom about 750 to about 3,000 MPa, and in some embodiments, from about1,000 to about 2,000 MPa, as determined in accordance with ASTM D638-10.The ethylene polymer may also have a melt flow index of from about 0.1to about 100 grams per 10 minutes, in some embodiments from about 0.5 toabout 50 grams per 10 minutes, and in some embodiments, from about 1 toabout 40 grams per 10 minutes, determined at a load of 2160 grams and at190° C., as determined in accordance with ASTM D1238-13 (or ISO 1133).

Multilayer films may be prepared by co-extrusion of the layers,extrusion coating, or by any conventional layering process. Any of avariety of techniques may generally be employed to form the film of thepresent invention. In certain embodiments, for example, the componentsof the film (e.g., ethylene polymer, nanoclay, compatibilizer, etc.) maybe individually supplied to a film forming system and blended togetheras the film is being formed. In such cases, the nanoclay may be in theform of a powder containing particles, such as described above.Alternatively, however, it is may be desirable to pre-blend the ethylenepolymer, nanoclay, and/or compatibilizer to form a masterbatch, which isthen subsequently supplied to the film forming system. Without intendingto be limited by theory, it is believed such a multi-step process canallow the nanoclay to be more uniformly oriented, thereby even furtherenhancing ductility. When supplied, the nanoclay may itself be in theform of a masterbatch, which may contain nanoclay particles blended witha polymer (e.g., ethylene polymer), or in the form of a powdercontaining particles.

To form a masterbatch, for example, the components may initially besupplied to twin screw extruder that includes co-rotating screwsrotatably mounted and received within a barrel (e.g., cylindricalbarrel), which may be heated. The components are moved downstream from afeed end to a discharge end by forces exerted by rotation of the screws.The ratio of the length to outer diameter (“L/D”) of the screws may beselected to achieve an optimum balance between throughput arid blenduniformity. For example, too large of an L/D value may increase theretention time to such an extent that the nanoclay degrades beyond thedesired level. On other hand, too low of an L/D value may not result inthe desired degree of blending or mixing. Thus, the L/D value istypically from about 25 to about 60, in some embodiments from about 35to about 55, and in some embodiments from about 40 to about 50. Thespeed of the screws may also be selected to achieve the desiredresidence time, shear rate, melt processing temperature, etc. Generally,an increase in product temperature is observed with increasing screwspeed due to the additional mechanical energy input into the system. Thefrictional energy results from the shear exerted by the turning screw onthe materials within the extruder and results in the fracturing of largemolecules. This results in lowering the apparent viscosity andincreasing the melt flow rate of the finished material. For example, thescrew speed may range from about 50 to about 400 revolutions per minute(“rpm”), in some embodiments from about 100 to about 300 rpm, and insome embodiments, from about 120 to about 280 rpm. As a result, meltprocessing may occur at a temperature of from about 100° C. to about500° C., in some embodiments, from about 150° C. to about 350° C., andin some embodiments, from about 150° C. to about 300° C. Typically, theapparent shear rate during melt processing may range from about 300seconds⁻¹ to about 10,000 seconds⁻¹, in some embodiments from about 500seconds⁻¹ to about 5000 seconds⁻¹, and in some embodiments, from about800 seconds⁻¹ to about 1200 seconds⁻¹. The apparent shear rate is equalto 4Q/□ R³, where Q is the volumetric flow rate (“m³/s”) of the polymermelt and R is the radius (“m”) of the capillary (e.g., extruder die)through which the melted polymer flows. Of course, other variables, suchas the residence time during melt processing, which is inverselyproportional to throughput rate, may also be controlled to achieve thedesired blending.

Once formed, the pre-blended masterbatch may be supplied to afilm-forming system. Any known technique may be used to form a film fromthe compounded material, including blowing, casting, fiat die extruding,etc. In one particular embodiment, the film may be formed by a blownprocess in which a gas (e,g., air) is used to expand a bubble of theextruded polymer blend through an annular die. The bubble is thencollapsed and collected in flat film form. Processes for producing blownfilms are described, for instance, in U.S. Pat. No. 3,354,506 to Raley;U.S. Pat. No. 3,650,649 to Schippers; and U.S. Pat. No. 3,801,429 toSchrenk et al., as well as U.S. Patent Application Publication Nos.2005/0245162 to McCormack, et al. and 2003/0068951 to Boggs, et al. Inyet another embodiment, however, the film is formed using a castingtechnique,

Referring to FIG. 1, for instance, one embodiment of a method forforming a cast film is shown. In this embodiment, the pre-blendedmasterbatch is supplied to an extruder 80 for melt processing. To helpachieve good alignment and orientation of the nanoclay, it is typicallydesired to use a single screw extruder during film formation. Suchsingle screw extruders are typically divided into three sections alongthe length of the screw. The first section is a feed section where thesolid material is introduced to the screw. The second section is amelting section where a majority of the melting of the solid occurs.Within this section, the screw generally possesses a tapered diameter toenhance melting of the polymer. The third section is the mixing section,which delivers the molten material in a constant amount for extrusion.The L/D ratio for the screw is typically from about 5 to about 50, insome embodiments from about 10 to about 40, and in some embodiments fromabout 15 to about 35. Such L/D ratios may be readily achieved in asingle screw extruder by using mixing section(s) that constitute only asmall portion of the length of the screw. The screw speed may likewiserange from about 5 to about 150 rpm, in some embodiments from about 10to about 100 rpm, and in some embodiments, from about 20 to about 80rpm. As a result, melt processing may occur at a temperature of fromabout 100° C. to about 500° C., in some embodiments, from about 150° C.to about 350° C., and in some embodiments, from about 150° C. to about300° C.

Once formed, the extruded material may be immediately chilled and cutinto pellet form. In the embodiment of FIG. 1, the extruded material iscast onto a casting roll 90 to form a single-layered precursor film 10a. if a multilayered film is to be produced, the multiple layers areco-extruded together onto the casting roll 90. The casting roll 90 mayoptionally be provided with embossing elements to impart a pattern tothe film. Typically, the casting roll 90 is kept at temperaturesufficient to solidify and quench the sheet 10 a as it is formed, suchas from about 20 to 60° C. If desired, a vacuum box may be positionedadjacent to the casting roll 90 to help keep the precursor film 10 aclose to the surface of the roll 90. Additionally, air knives orelectrostatic pinners may help force the precursor film 10 a against thesurface of the casting roll 90 as it moves around a spinning roll. Anair knife is a device known in the art that focuses a stream of air at avery high flow rate to pin the edges of the film.

Once cast, the film 10 a may then be optionally oriented in one or moredirections to further improve film uniformity and reduce thickness. Inthe case of sequential orientation, the “softened” film is drawn byrolls rotating at different speeds of rotation such that the sheet isstretched to the desired draw ratio in the longitudinal direction(machine direction). If desired, the uniaxially oriented film may alsobe oriented in the cross-machine direction to form a “biaxiallyoriented” film. For example, the film may be clamped at its lateraledges by chain clips and conveyed into a tenter oven. In the tenteroven, the film may be reheated and drawn in the cross-machine directionto the desired draw ratio by chain clips diverged in their forwardtravel.

Referring again to FIG. 1, for instance, one method for forming auniaxially oriented film is shown. As illustrated, the precursor film 10a is directed to a film-orientation unit 100 or machine directionorienter (“MDO”), such as commercially available from Marshall andWillams, Co. of Providence, R.I. The MDO has a plurality of stretchingrolls (such as from 5 to 8) which progressively stretch and thin thefilm in the machine direction, which is the direction of travel of thefilm through the process as shown in FIG. 1. While the MDO 100 isillustrated with eight rolls, it should be understood that the number ofrolls may be higher or lower, depending on the level of stretch that isdesired and the degrees of stretching between each roll. The film may bestretched in either single or multiple discrete stretching operations.It should be noted that some of the rolls in an MDO apparatus may not beoperating at progressively higher speeds. If desired, some of the rollsof the MOO 100 may act as preheat rolls. If present, these first fewrolls heat the film 10 a above room temperature. The progressivelyfaster speeds of adjacent rolls in the MDO act to stretch the film 10 a.The rate at which the stretch rolls rotate determines the amount ofstretch in the film and final film weight. The resulting film 10 b maythen be wound and stored on a take-up roll 60. While not shown here,various additional potential processing and/or finishing steps known inthe art, such as slitting, treating, aperturing, printing graphics, orlamination of the film with other layers (e.g., nonwoven web materials),may be performed without departing from the spirit and scope of theinvention.

III. Laminates

Although by no means required, it may be desirable in certain cases tolaminate an additional material to the nanocomposite film of the presentinvention, such as fibrous webs (e.g., nonwoven webs), other films,foams, strands, etc. Exemplary polymers for use in forming nonwoven webmaterials may include, for instance, polyolefins, e.g., polyethylene,polypropylene, polybutylene, etc.; polytetrafluoroethylene; polyesters,e.g., polyethylene terephthalate and so forth; polyvinyl acetate;polyvinyl chloride acetate; polyvinyl butyral; acrylic resins, e.g.,polyacrylate, polymethylacrylate, polymethylmethacrylate, and so forth;polyamides, e.g., nylon; polyvinyl chloride; polyvinylidene chloride;polystyrene; polyvinyl alcohol; polyurethanes; polylactic acid;copolymers thereof; and so forth. If desired, biodegradable polymers,such as those described above, may also be employed. Synthetic ornatural cellulosic polymers may also be used, including but not limitedto, cellulosic esters; cellulosic ethers; cellulosic nitrates:cellulosic acetates; cellulosic acetate butyrates; ethyl cellulose;regenerated celluloses, such as viscose, rayon, and so forth. It shouldbe noted that the polymer(s) may also contain other additives, such asprocessing aids or treatment compositions to impart desired propertiesto the fibers, residual amounts of solvents, pigments or colorants, andso forth. If desired, the nonwoven facing used to form the laminate mayitself have a multi-layer structure. Suitable multi layered materialsmay include, for instance, spunbond/meltblown/spunbond (SMS) laminatesand spunbond/meltblown (SM) laminates. Various examples of suitable SMSlaminates are described in U.S. Pat. No. 4,041,203 to Brock et al.; U.S.Pat. No. 5,213,881 to Timmons, et al.: U.S. Pat. No. 5,464,688 toTimmons, et al.; U.S. Pat. No. 4,374,888 to Bornslaeger; U.S. Pat. No.5,169,706 to Collier, et al.; and U.S. Pat. No. 4,766,029 to Brock etal. The basis weight of the nonwoven facing may generally vary, such asfrom about 5 grams per square meter (“gsm”) to 120 gsm, in someembodiments from about 10 gsm to about 70 gsm, and in some embodiments,from about 15 gsm to about 35 gsm. When multiple nonwoven web materials,such materials may have the same or different basis weights.

IV. Applications

The film of the present invention is particularly suitable for use as apackaging film, such as an individual wrap, packaging pouches, bundlefilms, or bags for the use of a variety of articles, such as foodproducts, paper products (e.g., tissue, wipes, paper towels, etc.),absorbent articles, etc. Various suitable pouch, wrap, or bagconfigurations for absorbent articles are disclosed, for instance, inU.S. Pat. No. 6,716,203 to Sorebo, et al. and U.S. Pat. No. 6,380,445 toModer, et al., as well as U.S. Patent Application Publication No.2003/0116462 to Sorebo, et al.

The present invention may be better understood with reference to thefollowing examples,

Test Methods Mechanical Properties:

The strip tensile strength values were determined in substantialaccordance with ASTM Standard D638-99. A constant-rate-of-extension typeof tensile tester was employed. The tensile testing system was an MTSSynergy 200 tensile frame. The tensile tester was equipped withTESTWORKS 4.08B software from MTS Corporation to support the testing.The load cell was 100 Newtons. The film samples were initially cut intodog-bone shapes with a center width of 3.0 mm before testing. Thesamples were held between grips having a front and back face measuring25.4 millimeters×76 millimeters. The grip faces were rubberized, and thelonger dimension of the grip was perpendicular to the direction of pull.The grip pressure was pneumatically maintained at a pressure of 40pounds per square inch. The tensile test was run using a gauge length of18.0 millimeters and a break sensitivity of 40%. Five samples weretested by applying the test load along the machine-direction and fivesamples were tested by applying the test load along the cross direction.During the test, samples were stretched at a crosshead speed of about127 millimeters per minute until breakage occurred. The modulus, peakstress, peak elongation (percent strain at break), and energy per volumeat break were measured in the machine direction (“MD”) and cross-machinedirections (“CD”).

Noise Level:

Noise levels of film samples may be tested in an apparatus comprised ofa test chamber, a control chamber, and a sound level meter. The purposeof the apparatus is to manipulate an article in a controlled noiseenvironment, and to accurately quantify the noise produced by themovement of the sample, in general terms, a sample is physicallydeformed within the test apparatus to generate a noise level. As usedherein, the “noise level” refers to the equivalent continuous noiselevel (referred to as “L_(EQ)” or “L_(AT)”), which is the time averagesound level (expressed in units of dB) as determined according to thefollowing equation:

$L_{eq} = {10\mspace{14mu} {\log \left\lbrack {\frac{1}{t_{2} - t_{1}}{\int_{t_{1}}^{t_{2}}{\frac{p_{A}^{2}}{p_{0}^{2}}\ {t}}}} \right\rbrack}}$

p₀ is a reference pressure level (typically 20 μPa);

p_(A) is the acquired sound pressure;

t is time;

t₁ is the start time for measurement; and

t₂ is the end time for measurement.

This value is also described in IEC 61672-1 (2013).

The testing apparatus is illustrated in FIGS. 7-9. The testing apparatus200 includes a test chamber 201 and a control chamber 202. The testchamber 201 includes a door 203, a top wall 204, a bottom wall 205, twoside walls 206 and 207, and a rear wall 208. The door and each wall areconstructed of 0.25-inch (0.635 cm) thick 6061 grade anodized aluminum.The door 203 and rear wall 208 are each 36 inches (91.4 cm) in heightand 24 inches (61.0 cm) in width. The test chamber side walls 206 and207 are each 36 inches (91.4 cm) high and 18 inches (45.7 cm) wide. Thetest chamber top and bottom panels are each 24 inches wide (61.0 cm) and18 inches (45.7 cm) long. The interior surface of the door 203 and eachwall 204-208 has applied thereto two-inch thick polyurethanesound-dampening foam 209, available from Illbruck Inc. under the brandname SONEX and stock number SOC-2. As shown, a sound level meter support216 extends perpendicularly outward from side wall 206 just below amicrophone orifice 217. The microphone orifice 217 is positioned 14.5centimeters above the floor of the bottom wall 205, and is furthercentered between the door 203 and the rear wall 208. The sound levelmeter support 216 is constructed of aluminum and is bolted (not shown)to side wall 206. The control chamber 202 includes a front wall 230, twoside wails 231 and 232, a top wall 233, and a bottom wall 234. Each wallis constructed of 0.125-inch (0.3175 cm) thick 6061 grade anodizedaluminum. The front wall 230 is 36 inches (91.4 cm) high and 24 inches(61.0 cm) wide. The control chamber side walls 231 and 232 are each 36inches high (91.4 cm) and 12 inches (30:5 cm) wide. The control chambertop and bottom walls 233 and 234 are each 24 inches (61.0 cm) wide and12 inches (30.5 cm) long. The control chamber 202 is bolted (not shown)to the outer surface of rear wall 208 along seam 270 (FIG. 8). The outersurface of the rear wall 208, and the front wall 230, two side walls 231and 232, top wall 233, and bottom wall 234 of the control chamber 202are each coated with 0.600-inch (1.524 cm) thick sound insulatingmaterial, part number NYC-600BE, available from Small Parts, Inc. Thetesting apparatus 200 further includes a sound level meter 220 (FIG. 9),such as a model 1900, equipped with a model OB-100 octave filter set,both available from Quest Technologies, a company having offices inOconomowoc, Wis. The sound level meter is supported by a model QC-20calibrator and QuestSuite master module software, each also availablefrom Quest Technologies. The software is installed or a personalcomputer (not shown). During operation of the testing apparatus, thesound level meter 220 rests in the sound level meter support 216. Thesound level meter includes a microphone 221 extending 4.75 inches (12centimeters) therefrom.

Although by no means required, the apparatus may also contain featuresfor automatically deforming a sample during a test. For example, theapparatus may contain a lower slide bracket 210, a six-inch (15.24 cm)high Series A1500 Model available from Velmex, Inc., which extends fromthe bottom wall 205 into the test chamber 201, and a lower clamp 211that is affixed to the lower slide bracket 210. An eyelet 212 (FIG. 9)may optionally extend from the top wall 204 into the test chamber 201,and an optional lanyard 213 extends through the eyelet 212. One end ofthe lanyard 213 extends into the test chamber 201, and has an upperclamp 214 affixed thereto. The other end of the lanyard 213 extends intothe control chamber 202 through a lanyard orifice 215, which is ⅝ inch(16 mm) in diameter. The lanyard may be a premium-braid, 80-lb testSpiderwire®, part number SB80G-300, manufactured by Johnson WorldwideAssociates (JWA), Inc.

Prior to testing a specimen using the testing apparatus 200, thefollowing steps are followed:

1. Calibrate the sound level meter 220 following the instructions in themanufacturer's manual.

2. Insert the full length of the microphone 221 into the testing chamber201 (it should extend past the wall and sound dampening materialapproximately 2.5 inches (6.35 cm)), positioned at a 90-degree angle toside wall 206. Allow the sound level meter 220 to rest in the soundlevel meter support 216.

3. Activate the sound level meter per the manufacturer's instructionmanual. This will collect the ambient noise inside the cavity of thetest chamber 200.

4. Set the octave filter to 2,000 or 4,000 Hz and take a reading foreach test conducted by activating the sound level meter unto the testinghas been completed.

Having calibrated the testing apparatus 200 and having identified theambient noise, five (5) specimens of a film sample may then bephysically deformed approximately 15 to 20 centimeters from themicrophone within the test apparatus.

The film samples in the Examples below were manually deformed asfollows:

1. Open the dominant hand with the palm facing upward;

2. Place the film sample in the palm of the dominant hand;

3. Compress the test specimen by making a gentle fist;

4. Quickly open the hand and release the test specimen; and

5. Repeat this four (4) more times to equate to five (5) film“crumples.”

Regardless of the manner of physical deformation, the tests rangedbetween 1 to 2 seconds in duration. All tests involved starting thesound level meter, completing the respective product manipulation, andthen stopping the sound level meter. The chamber door was allowed toremain open during testing to accommodate the arms and hands of thetester, as well as the motions of the product manipulation protocols.The ambient noise outside of the apparatus was quiet and was the sameduring calibration (including measuring the ambient noise level) andtesting of the sample,

Control 1

A film layer was formed from Dowlex™ EG 2244G using a HAAKE Rheomex®252p single screw extruder and a 6 cast film die. Dowlex™ EG2244G is alinear low density polyethylene having a melt flow index of 1.0 g/10minutes at 190° C. (Dow Chemical). The screw had a diameter of 19.05 mmand an L/D of 25 (L is the screw length). A chill roll was used to cooland flatten the polymer as it exited the cast film die. The screw speedwas maintained at 60 rpm for a target thickness of 25.4 micrometers. Thefour controlled temperature zones from the first heating zone to the dieadaptor were set at 180° C., 180° C., 180° C., and 180C, respectively.The torque on the extruder was 24 N-m and the pressure at the die was520 psi.

Control 2

A film layer was formed as described in Control 1, except that thetarget thickness was 12.7 micrometers and the screw speed was about 30rpm.

Control 3

A film layer was formed from DPDA-3320 N7 using a HAAKE Rheomex® 252psingle screw extruder and a 6″ cast film die. DPDA-3320 N7 is a highdensity polyethylene having a melt flow index of 2.0 g/10 minutes at190° C. (Dow Chemical). The screw had a diameter of 19.05 mm and an L/Dof 25 (L is the screw length). A chill roll was used to cool and flattenthe polymer as it exited the cast film die. The screw speed wasmaintained at 40 rpm for a target thickness of 12.7 micrometers. Thefour controlled temperature zones from the first heating zone to the dieadaptor were set at 170° C., 180° C., 185° C., and 190° C.,respectively. The torque on the extruder was 20 N-m and the pressure atthe die was 493 psi.

Control 4

A film layer was formed from 80% Dowlex™ EG 2244G as described inControl 1, and 20% DPDA-3320 N7 using a HAAKE Rheomex® 252p single screwextruder and a 6″ cast film die. The screw had a diameter of 19.05 mmand an L/D of 25 (L is the screw length). A chill roll was used to cooland flatten the polymer as it exited the cast film die. The screw speedwas maintained at 40 rpm for a target thickness of 12.7 micrometers. Thefour controlled temperature zones from the first heating zone to the dieadaptor were set at 170° C., 180° C., 185° C., and 190° C.,respectively. The torque on the extruder was 15 N-m and the pressure atthe die was 638 psi.

EXAMPLE 1

A film layer was formed from 90 wt. % of a first masterbatch and 10 wt.% of a second masterbatch. The first masterbatch was formed by dryblending 80 wt. % Dowlex™ 2244G (LLDPE) and 20 wt. % DPDA-3320 N7 (HDPE)and the second masterbatch was formed by dry blending 80 wt. % NanoMax™LDPE (Nanocor, Inc.) and 20 wt. % NanoMax™ HDPE (Nanocor, Inc). NanMax™LDPE contains 50 wt. % Nanomer™ nanoclay (quaternary ammoniumsurface-modified montmorillonite), 30 wt. % LDPE, and 20% LDPE graftedwith maleic anhydride. NanoMax™ HDPE contains 50 wt. % Nanomer™ nanoclayand 30 wt. % HDPE and HDPE grafted with maleic anhydride. The materialswere delivered through two K-Tron gravimetric feeders and melt blendedtogether using a Werner & Pfleiderer (W&P) ZSK-30 co-rotating, twinscrew extruder. The extruder had 14 processing barrels, with 13 heatedbarrels. Three barrels are open barrels. The outer diameters of thescrews were 30 mm and the inner screw diameters were 21.3 mm. Thelengths of the screws were 1328 mm and the total processing sectionlength was 1338 mm. The zones had a processing temperature of 171° C.,181° C., 188° C., 190° C., 191° C., 195° C., and 200° C., respectively.The melt temperature was about 224° C. and the pressure was about260-290 psi. The compounding speed in the twin screw extruder was set as250 rpm.

Once formed, the blends were formed into a film layer using a HAAKEsingle screw extruder as described in Control 1. The screw speed wasmaintained at 35 rpm for a target thickness of 12.7 micrometers. Thefour controlled temperature zones from the first heating zone to the dieadaptor were set at 190° C., 200° C., 200° C., and 200° C.,respectively. The torque on the extruder was 12 N-m and the pressure atthe die was 406 psi.

EXAMPLE 2

A film layer was formed from 90 wt. % of a first masterbatch and 10 wt.% of a second masterbatch. The first masterbatch was formed by dryblending 60 wt. % Dowlex™ 2244G (LLDPE) and 40 wt. % DPDA-3320 N7 (HDPE)and the second masterbatch was formed by dry blending 60 wt. % NanoMax™LDPE and 40 wt. % NanoMax™ HDPE. The materials were delivered throughtwo K-Tron gravimetric feeders and melt blended together using a Werner& Pfieiderer (W&P) ZSK-30 co-rotating, twin screw extruder as describedin Example 1. The zones had a processing temperature of 166° C., 183°C., 191° C., 190° C., 191° C., 195° C., and 201° C., respectively. Themelt temperature was about 227° C. and the pressure was about 220-340psi. The compounding speed in the twin screw extruder was set as 250rpm. Once formed, the blends were formed into a film layer using a HAAKEsingle screw extruder as described in Control 1. The screw speed wasmaintained at 33 rpm for a target thickness of 12.7 micrometers. Thefour controlled temperature zones from the first heating zone to the dieadaptor were set at 190° C., 200° C., 200° C., and 200° C.,respectively. The torque on the extruder was 14 N-m and the pressure atthe die was 406 psi.

EXAMPLE 3

A film layer was formed from 90 wt. % of a first masterbatch and 10 wt.% of a second masterbatch. The first masterbatch was formed by dryblending 40 wt. % Dowlex™ 2244G (LLDPE) and 60 wt. % DPDA-3320 N7 (HDPE)and the second masterbatch was formed by dry blending 40 wt. % NanoMax™LDPE and 60 wt. % NanoMax™ HDPE. The materials were delivered throughtwo K-Tron gravimetric feeders and melt blended together using a Werner& Pfleiderer (W&P) ZSK-30 co-rotating, twin screw extruder as describedin Example 1, The zones had a processing temperature of 169° C., 177°C., 191° C., 191° C., 190° C., 195° C., and 200° C., respectively. Themelt temperature was about 225° C. and the pressure was about 280-320psi. The compounding speed in the twin screw extruder was set as 250rpm. Once formed, the blends were formed into a film layer using a HAAKEsingle screw extruder as described in Control 1. The screw speed wasmaintained at 35 rpm for a target thickness of 12.7 micrometers. Thefour controlled temperature zones from the first heating zone to the dieadaptor were set at 190° C., 200° C., 200° C., and 200° C.,respectively. The torque on the extruder was 16 N-m and the pressure atthe die was 435 psi.

EXAMPLE 4

A film layer was formed from 90 wt. % of a first masterbatch and 10 wt.% of a second masterbatch. The first masterbatch was formed by dryblending 20 wt. % Dowlex™ 2244G (LLDPE) and 80 wt. % DPDA-3320 N7 (HDPE)and the second masterbatch was formed by dry blending 20 wt. % NanoMax™LDPE and 80 wt. % NanoMax™ HDPE. The materials were delivered throughtwo K-Tron gravimetric feeders and melt blended together using a Werner& Pfleiderer (W&P) ZSK-30 co-rotating, twin screw extruder as describedin Example 1. The zones had a processing temperature of 170° C., 180°C., 190° C., 191° C., 190° C., 195° C., and 200° C., respectively. Themelt temperature was about 226° C. and the pressure was about 280-320psi. The compounding speed in the twin screw extruder was set as 250rpm. Once formed, the blends were formed into a film layer using a HAAKEsingle screw extruder as described in Control 1. The screw speed wasmaintained at 35 rpm for a target thickness of 12.7 micrometers. Thefour controlled temperature zones from the first heating zone to the dieadaptor were set at 190° C. 200° C., 200° C., and 200° C., respectively.The torque on the extruder was 16 N-m and the pressure at the die was420 psi.

The film layers of Examples 1-4 were then conditioned overnight at 23±2°C. and 50±5% RH and subjected to mechanical testing as described above.The results are set forth below in Table 1.

TABLE 1 Mechanical Properties Avg. Energy Avg. Per Peak Avg. Peak Avg.Volume at Wt. Ratio Stress Elongation Modulus Break LLDPE LDPE HDPE of(LLDPE + Nanoclay (MPa) (%) (MPa) (J/cm³) Example (wt. %) (wt. %) (wt.%) LDPE)/HDPE (wt. %) MD CD MD CD MD CD MD CD Control 4 60 — 40 1.5 — 5728 365 782 211 221 82 106 1 72 4 19 4.0 5 52 28 340 850 230 210 93 126 254 3 38 1.5 5 55 29 330 900 280 280 98 147 3 36 2 57 0.7 5 52 29 320 930320 340 93 158 4 18 1 76 0.3 5 56 28 350 900 410 500 107 157

As indicated, the mechanical properties (e.g., modulus) generallyimproved with the incorporation of nanoclay.

EXAMPLE 5

Film layers were formed from blends containing various percentages ofLLDPE (Dowlex™ EG 2244G) and a nanoclay masterbatch (Nanocor™ availablefrom Nanocor, Inc.), as reflected below in Table 2. The nanoclaymasterbatch contained 50 wt % Nanomer™ nanoclay (quaternary ammoniumsurface-modified montmorillonite) and 30 wt. % low density polyethyleneand 20% maleic anhydride grafted polyethylene. The blends were formedusing a Werner & Pfleiderer (W&P) ZSK-30 co-rotating, twin screwextruder. The extruder had 14 processing barrels, with 13 heatedbarrels. Three barrels are open barrels. The outer diameters of thescrews were 30 mm and the inner screw diameters were 21.3 mm. Thelengths of the screws were 1328 mm and the total processing sectionlength was 1338 mm. The zones had a processing temperature of 170° C.,180° C., 190° C., 190° C., 190° C., 190° C., and 180° C., respectively.The melt temperature was about 202° C. and the pressure was about 60-80psi. The compounding speed in the twin screw extruder was set as 250rpm.

Once formed, the blends were formed into a film layer having a targetthickness of 28 micrometers using a HAAKE single screw extruder asdescribed in Control 1. The resulting samples were then conditionedovernight at 23±2° C. and 50±5% RH and subjected to mechanical testingas described above. The results are set forth below in Table 2.

TABLE 2 Mechanical Properties of the Films of Example 5 Avg. Avg. EnergyPer Peak Avg. Peak Avg. Volume at Nanoclay Stress Elongation ModulusBreak LLDPE Masterbatch (MPa) (%) (MPa) (J/cm³) (wt. %) (wt. %) MD CD MDCD MD CD MD CD Control 1 100 — 36 26 544 759 61 55 76 87 Example 5 96 441 31 625 859 116 115 99 111 90 10 40 34 591 903 128 143 105 140 84 1640 33 581 873 165 154 112 138

As indicated, the mechanical properties (e.g., peak elongation)generally improved with the incorporation of nanoclay. In the machinedirection (MD), a higher amount of nanoclay led to a slightly lowerstrain-at-break and higher elastic modulus due to the rigid nature ofnanoclay, but the elongation in MC and CD are still higher than thecontrol film without nanoclay, although the peak stress wasapproximately the same.

The film of Example 5 (10 wt. % nanoclay masterbatch) was also analyzedusing X-ray diffraction and transmission electron microscopy. Theresults are shown in FIGS. 2-3. As depicted in FIG. 2, only a small peakwas observed at an angle of about 7°, which indicates that only a smallportion of the nanoclay remained unexfoliated or undispersed. This isfurther evidenced by the transmission electron microphotographs shown inFIG. 3. Namely, FIG. 3(a) shows that the nanoclay was well dispersed inthe film and FIG. 3(b) shows that the nanoclay was exfoliated intosingle platelets (FIG. 3(b)) and dispersed in orientation. Minornanoclay clusters were also seen in the film as represented by thecircles.

Dynamic rheology testing was also performed on Control 1 and the samplescontaining 4 wt. %, 10 wt. %, and 16 wt. % of the nanoclay masterbatch.The results are shown in FIGS. 4-6. In the terminal (low frequency)zone, the neat LLDPE melt demonstrated a typical liquid likebehavior—logarithmic storage modulus (G′) vs, logarithmic frequency (γ)showed a smooth linear relationship (lower curve in FIG. 4). Theremaining films containing the nanoclay masterbatch not only exhibitedmuch higher G′ and complex viscosity (η*) values than neat LLDPE, butalso demonstrated drastically different terminal behaviors. Irrespectiveof frequency, G′ increased monotonically with increasing nanoclaycontent in the blends (FIG. 4). The viscoelastic response of the blendswas mainly altered at low frequencies, where G′ exhibited weak frequencydependences (FIG. 4). The small slope of log(G′) vs. log(γ) in the filmscontaining 10 wt. % nanoclay masterbatch (labeled as “90/10”) and 16 wt.% masterbatch (labeled as “84/16”) indicates a significantpseudo-solid-like behavior of the melt: This result suggests that aninterconnected network structure of anisometric filler—a characteristicsolid or gel-like structure had formed in the system. From FIG. 4, itcan be seen that the reduction of the slope of log(G′) vs. log(γ) withrespect to the neat polymer became phenomenal at 10% nanoclaymasterbatch (“90/10”), suggesting the critical content of nanoclay forthe percolation threshold.

On the other hand, in the terminal zone the plots of log(η) vs. log(γ)changed from a Newtonian (primary) plateau (lower curve in FIG. 5) forthe neat LLDPE to a clear shear-thinning behavior for the blends,providing more evidence of elastic behavior due to the solid networkstructure of nanoclay. Further evidence of the formation of apseudo-solid-like network of percolated threads is also noted in FIG. 6,where variations of storage modulus (G′) and loss modulus (G″) of theblend films vs, γ are compared. The nanofilms with a low nanoclaycontent (e.g., 4 wt. % nanoclay, “96/4”) displayed a lower G′ than G″over the whole frequency range. However, with the buildup of networkstructure, in the terminal zone G′ exceeded G″ due to the pseudo-solidlike behavior. At higher frequencies, crossover of G′ and G″ was noted,which was probably due to the destruction of the network structure athigh shear rates. Expectedly, the crossover of G′ and G″ was observedfor all those nanofilms with nanoclay contents equal to or higher than10%. It is worth mentioning that the crossover point shifted to higherfrequency with more nanoclay in the blends, as can been seen by the bluearrows in FIG. 6.

EXAMPLE 6

Film layers were formed as described in Example 5, except that thetarget thickness was 12.7 micrometers. The results are set forth belowin Table 3.

TABLE 3 Mechanical Properties of the Films of Example 6 Avg. Energy Avg.Per Peak Avg. Peak Avg. Volume at Nanoclay Stress Elongation ModulusBreak LLDPE Masterbatch (MPa) (%) (MPa) (J/cm³) (wt. %) (wt. %) MD CD MDCD MD CD MD CD Control 2 100 — 35 26 391 818 103 39 53 75 Example 6 96 437 29 452 809 137 129 68 91 90 10 44 28 404 852 185 133 80 97 84 16 4124 435 810 146 144 82 84 78 22 61 25 351 765 245 200 119 106 72 28 51 22294 631 291 233 88 80 66 34 52 19 254 540 396 250 88 67

As indicated, the mechanical properties (e.g., peak elongation)generally improved with the incorporation of nanoclay. In the machinedirection (MD), a higher amount of nanoclay led to a slightly lowerstrain-at-break and higher elastic modulus due to the rigid nature ofnanoclay, although the peak stress was approximately the same.

EXAMPLE 7

Film layers were formed from a blend containing 96 wt. % Dowlex™ EG2244G and 4 wt. % of a Nanocor™ masterbatch. The blend was formed usinga Werner & Pfieiderer (W&P) ZSK-30 co-rotating, twin screw extruder asdescribed in Example 5, except that the screw speed was 150 rpm. Theblend was formed into film having a target thickness of 27.94micrometers and 12.7 micrometers using a HAAKE single screw extruder asdescribed in Control 1 and 2. The resulting samples were thenconditioned overnight at 23±2° C. and 50±5% RH and subjected tomechanical testing as described above. The results are set forth belowin Table 4.

TABLE 4 Mechanical Properties of the Films of Example 7 Avg. Energy Avg.Per Peak Avg. Peak Avg. Volume Nanoclay Stress Elongation Modulus atBreak Thickness LLDPE Masterbatch (MPa) (%) (MPa) (J/cm³) (μm) (wt. %)(wt. %) MD CD MD CD MD CD MD CD Control 1 27.94 100 — 36 26 544 759 6155 76 87 Control 2 12.70 100 — 35 26 391 818 103 39 53 75 Example 727.94 96 4 41 33 641 912 121 120 98 127 12.70 96 4 41 29 473 815 154 12272 99

EXAMPLE 8

A film layer was formed from a blend containing 93 wt. % Dowlex™ EG2244G, 5 wt. % Nanomer™ 1.44P (quaternary ammonium surface-modifiedmontmorillonite), and 2 wt. % of Fusabond® MB-528D, which is a graftcopolymer of polyethylene and maleic anhydride available from DuPont.The film layer was formed on a HAAKE single-screw extruder. The screwhad a diameter of 19.05 mm and an L/D of 25 (L is the screw length). Achill roll was used to cool and flatten the polymer as it exited thecast film die. The screw speed was maintained at 20 rpm. The fourcontrolled temperature zones from the first heating zone to the dieadaptor were set at 180° C., 180° C., 180° C., and 190° C.,respectively. The die pressure was 19 bar and the torque was 7 N-m.

EXAMPLES 9-15

Various films were formed from the film of Example 8 and one or moreadditional film layers. The additional film layers were formed on aHAAKE single-screw extruder using the materials and conditions set forthbelow:

Die Die Speed Zone 1 Zone 2 Zone 3 Temp pressure Torque Film Material(RPM) (° C.) (° C.) (° C.) (° C.) (Bar) (N · m) A 100% Dowlex ™ EG 20180 180 180 190 27 17 2244G B 100% M3661 20 180 180 180 190 15 7 C 100%DPDA-3220 N 7 20 180 180 180 190 24 12 D 100% Escorene ™ Ultra 50 180180 180 190 20 7 LD 706.15 E 100% Vistamaxx ™ 3980 10 180 180 180 190 115

M3661 is a polypropylene available from Total Petrochemicals USA(Houston, Tex.). DPDA-3220 N 7 is a high density polyethylene with amelt flow of 2.0 g/10 minutes at 190° C., and available from DowChemical Company (Midland, Mich.). Escorene™ Ultra LD 706.15 is ethylenevinyl acetate (“EVA”) available from ExxonMobil (Houston, Tex.).Vistamaxx™ 3980, a propylene-based elastomer available from ExxonMobil(Houston, Tex.).

The films were formed using a 15-ton hydraulic Carver press. The presshad two platens set at 205° F. The dwell time was 2 minutes under a13,000-lb force. The films had the following configurations:

Exam- ple 1^(st) Outer Layer Core Layer 2^(nd) Outer Layer 9 Film A Filmof Example 8 Film A 10 Film C Film of Example 8 Film C 11 Film A Film ofExample 8 Film C 12 Film A — Film of Example 4 13 Film of Example 4 FilmA Film of Example 4 14 Film D Film of Example 8 Film D 15 Film E Film ofExample 8 Film E

Once formed, the films were conditioned at 75° F./50% relative humidity.After conditioning 24 hours, the films were removed from conditioningand subjected to mechanical testing as described above. The results areset forth below in Table 5.

TABLE 5 Mechanical Properties of the Films of Examples 9-15 Energy perVolume Peak Peak at Thickness Stress Elongation Modulus Break Example(mil) (MPa) (%) (MPa) (J/cm³) 9 MD 1.8 41 408 165 79 CD 2.1 14 428 33246 10 MD 1.9 20 327 295 57 CD 1.3 5 65.6 46 3 11 MD 1.9 21 253 226 33 CD1.9 9 445 272 36 12 MD 1.3 6 198 98 11 CD 1.4 5 66 46 3.0 13 MD 2.0 9412 159 28 CD 2.1 6 122 149 14 14 MD 4.7 9 450 57 33 CD 5.1 8 429 61 2815 MD 1.3 12 473 94 39 CD 1.2 13 494 859 32

EXAMPLE 16

A film layer was formed from a blend containing 90 wt. % Dowlex™ EG2244G and 10 wt. % of a nanoclay masterbatch. The nanoclay masterbatchcontained a blend of 50 wt. % Clayton™ HY, 30 wt. % Dowlex EG2244G, and20 wt. % of Fusabond® MB-528D. Clayton™ HY is an organoclay powdertreated with quaternary ammonium solution and is available from BYKAdditives, Inc. (Gonzales Tex.). The nanoclay masterbatch was formed ona Thermo Prism USALab16 co-rotating twin screw microextruder (ThermoElectron Corporation; Stone, England) having an L/D ratio of 40:1. TheLLDPE and Fusabond® components were fed through the pellet feeders andthe Clayton™ HY organoclay powder was fed using a powder feeder. Theprocessing temperatures along the 10-zone extruder were 170° C., 180°C., 185° C., 180° C., 185° C., 185° C., 185° C., 185° C., 185° C., and180° C., respectively. The melt pressure was about 30 psi and thecompounding speed was 100 rpm. The LLDPE and nanoclay masterbatch werethereafter compounded on a ZSK-30 twin screw extruder as described inExample 5. A film layer was thereafter produced from the resulting blendusing a HAAKE single-screw extruder as described in Control 1.

EXAMPLE 17

A film layer was formed as described in Example 16, except that thenanoclay used is Cloisite™ 15A, instead of Clayton™ HY.

EXAMPLE 18

A film layer was formed as described in Example 16, except that thenanoclay used is Cloisite™ 30B, instead of Clayton™ HY.

EXAMPLE 19

A film layer was formed as described in Example 16, except that thenanoclay used is Cloisite™ 93A, instead of Clayton™ HY.

EXAMPLE 20

A film layer was formed as described in Example 16, except that thenanoclay used is Cloisite™ Na⁺, instead of Clayton™ HY.

These films were conditioned at 75° F.50% relative humidity. Afterconditioning 24 hours, the films were removed from conditioning andsubjected to mechanical testing as described above. The results are setforth below in Table 6.

TABLE 6 Mechanical Properties of the Films of Examples 16-20 Energy perThick- Peak Peak Volume at ness Stress Elongation Modulus Break Example(mil) (MPa) (%) (MPa) (J/cm³) 16 MD 1 60 ± 2 543 ± 4  184 ± 13 144 ± 3 CD 1 44 ± 3 859 ± 31 164 ± 2  170 ± 21 17 MD 1 52 ± 6 541 ± 67 147 ± 12122 ± 21 CD 1 37 ± 3 826 ± 23 141 ± 11 138 ± 10 18 MD 1 31 ± 2 407 ± 19105 ± 9  54 ± 3 CD 1 19 ± 2 756 ± 27  79 ± 11  65 ± 10 19 MD 1 55 ± 2504 ± 15 178 ± 9  121 ± 8  CD 1 40 ± 2 846 ± 21 157 ± 7  164 ± 11 20 MD1 20 ± 1 246 ± 20 68 ± 5 26 ± 2 CD 1 11 ± 2 673 ± 51 78 ± 6 44 ± 4

EXAMPLE 21

A film layer was formed as described in Example 16, except that thetarget thickness was 12.7 micrometers and the screw speed was about 30rpm.

EXAMPLE 22

A film layer was formed as described in Example 17, except that thetarget thickness was 12.7 micrometers and the screw speed was about 30rpm.

EXAMPLE 23

A film layer was formed as described in Example 18, except that thetarget thickness was 12.7 micrometers and the screw speed was about 30rpm.

EXAMPLE 24

A film layer was formed as described in Example 19, except that thetarget thickness was 12.7 micrometers and the screw speed was about 30rpm.

EXAMPLE 25

A film layer was formed as described in Example 20, except that thetarget thickness was 12.7 micrometers and the screw speed was about 30rpm,

These films were conditioned at 75° F./50% relative humidity. Afterconditioning 24 hours, the films were removed from conditioning andsubjected to mechanical testing as described above. The results are setforth below in Table 7.

TABLE 7 Mechanical Properties of the Films of Examples 21-25 Energy perThick- Peak Peak Volume at ness Stress Elongation Modulus Break Example(mil) (MPa) (%) (MPa) (J/cm³) 21 MD 0.5 71 ± 4 355 ± 29 250 ± 53 120 ±5  CD 0.5 38 ± 2 832 ± 16 178 ± 11 156 ± 6  22 MD 0.5 56 ± 1 335 ± 39176 ± 11 85 ± 7 CD 0.5 28 ± 2 790 ± 35 146 ± 19  99 ± 11 23 MD 0.5 37 ±2 279 ± 24 163 ± 29 55 ± 3 CD 0.5 23 ± 0 737 ± 18 158 ± 9  94 ± 1 24 MD0.5 68 ± 1 339 ± 16 237 ± 28 111 ± 6  CD 0.5 35 ± 2 824 ± 38 179 ± 21152 ± 12 25 MD 0.5 23 ± 1 142 ± 5  145 ± 2  22 ± 3 CD 0.5  7 ± 1 538 ±29 129 ± 9  26 ± 1

Control 5

A commercial film was tested that is produced by Quanxing Plastics, Inc.The film had a basis weight of 18 grams per square meters and was castextruded from a blend containing 35 to 45 wt. % high densitypolyethylene (HDPE 5070), 20 to 30 wt. % low density polyethylene (LDPELD100AC), 25 to 35 wt. % linear low density polyethylene (LLDPE 7050),and 5 to 10 wt. % of a titanium dioxide masterbatch (1605H). Amicro-embossed pattern having a depth of 1 to 5 micrometers was formedon a surface of the film.

EXAMPLE 26

A film was formed from a blend containing 93.5 wt. % of a polyethylenemasterbatch, 4.5 wt. % of Clayton™ HY, and 2 wt. % of Fusabond® E-528,which is a graft copolymer of polyethylene and maleic anhydrideavailable from DuPont. The polyethylene masterbatch contained 35 to 45wt. % high density polyethylene (HDPE 5070), 20 to 30 wt. % low densitypolyethylene (LDPE LD100AC), 25 to 35 wt. % linear low densitypolyethylene (LDPE 7050), and 5 to 10 wt. % of a titanium dioxidemasterbatch (1605H). Clayton™ HY is an organoclay powder treated withquaternary ammonium solution and is available from BYK Additives, Inc.(Gonzales Tex.). The blend was formed using a co-rotating, twin screwextruder available from Entek®. The extruder had 14 processing barrels,with 13 heated barrels. Three barrels are open barrels. The outerdiameter of the screws was 53 mm. The processing temperatures along theextruder were set as 175° C. and the compounding speed in the twinextruder was set as 700 rpm. The resultant strands were cooled in awater bath with 15 feet length in total. The cooled strand was thenpelletized and collected for the following film processing.

A film was thereafter produced from the resulting blend using asingle-screw extruder. The extruder has 8 processing barrels, with 7heated barrels with temperatures ranging from 175-210° C., The screwspeed was adjusted between 66.5 and 68.6 rpm depending on the requiredfilm thickness. The corresponding line speed was adjusted between 85 and90 meters per minute. The resulting film had a basis weight of 13.5grams per square meter. A micro-embossed pattern having a depth of 1 to5 micrometers was formed on a surface of the film.

EXAMPLE 27

A film was formed as described in Example 26, except that a deepembossing pattern having a depth of 5 to 15 micrometers was formed onthe surface.

The films of Control 5, Example 26, and Example 27 were then tested fornoise level as described herein. The tested films were rectangular andhad a size of 13.5 centimeters by 28.0 centimeters. The results areshown in Table 8 below.

TABLE 8 Noise Level of Films at 4,000 Hz Noise Level (dB) NormalizedNoise Level Control 5 46.0 2.6 Example 26 39.6 2.2 Example 27 38.0 2.1Ambient 17.7 —

As indicated above, the film of Examples 26 and 27 showed considerablereduction in noise level compared with the control sample.

EXAMPLE 28

A blown film was formed from a blend containing 84.5 wt. % Dowlex™ EG2047G, 4.5 wt. % of Clayton™ HY, 2.0 wt. % of Fusabond® E-528, and 9.0wt. % Ampacet® 110313 (color additive, Ampacet Corporation). The blendwas formed using a co-rotating, twin screw extruder. The extruder had 14processing barrels, with 13 heated barrels having a length of 210 mm.The outer diameter of the screws was 53 mm. The processing temperaturesalong the extruder were set as 180° C. and the compounding speed in thetwin extruder was set as 750 rpm. The polyethylene was fed through onepellet feeder, the Fusabond® with Ampacet® additives were fed throughanother pellet feeder; and the nanoclay was fed through a powder throatfeeder. The film was formed on a single screw extruder with a monolayerblown film die. The line speed was 175 pounds per hour and thethicknesses of films were controlled at 1.5 mils. The melt temperaturewas controlled within range of 175-185° C.

The oxygen transmission rate of the film was determined to be 277cm³/in²*24 hours. A control sample containing only 95 wt. % Dowlex™2047G with 5 wt. % Ampacet® was also formed. The oxygen transmissionrate of the control film sample was determined to be 392 cm³/in²*24hours.

While the invention has been described in detail with respect to thespecific embodiments thereof. It will be appreciated that those skilledin the art, upon attaining an understanding of the foregoing, mayreadily conceive of alterations to, variations of, and equivalents tothese embodiments. According, the scope of the present invention shouldbe assessed as that of the appended claims and any equivalents thereto.

1. A packaging film having a thickness of about 50 micrometers or less,the film containing a core layer that is positioned adjacent to an outerlayer, wherein the core layer, the outer layer, or both are formed froma polymer composition, the polymer composition containing from about 70wt. % to about 99 wt. % of an ethylene polymer, from about 0.1 wt. % toabout 20 wt. % of a nanoclay having an organic surface treatment, andfrom 0.05 wt. % to about 15 wt. % of a polyolefin compatibilizer thatcontains an olefin component and a polar component.
 2. The packagingfilm of claim 1, wherein the ethylene polymer includes a copolymer ofethylene and an α-olefin.
 3. The packaging film of claim 1, wherein theethylene polymer includes linear low density polyethylene, low densitypolyethylene, high density polyethylene, or a mixture thereof.
 4. Thepackaging film of claim 1, wherein the nanoclay includes aphyllosilicate.
 5. The packaging film of claim 4, wherein thephyllosilicate includes a montmorillonite or a salt thereof.
 6. Thepackaging film of claim 1, wherein the nanoclay includes plateletshaving an average thickness of from about 0.2 to about 100 nanometers.7. The packaging film of claim 1, wherein the organic surface treatmentincludes a quaternary onium.
 8. The packaging film of claim 1, whereinthe polar component of the compatibilizer includes maleic anhydride. 9.The packaging film of claim 1, wherein the film exhibits a normalizedpeak elongation in the machine direction of about 15%/μm or more. 10.The packaging film of claim 1, wherein the film exhibits a normalizedpeak elongation in the cross-machine direction of about 40%/μm or more.11. The packaging film of claim 1, wherein the film exhibits anormalized ultimate tensile strength in the machine direction and/orcross-machine direction of from about 0.5 to about 20 MPa/μm.
 12. Thepackaging film of claim 1, wherein the film exhibits a normalizedYoung's modulus in the machine direction and/or cross-machine directionof from about 5 to about 50 MPa/μm.
 13. The packaging film of claim 1,wherein the outer layer contains the polymer composition.
 14. Thepackaging film of claim 13, wherein the ethylene polymer includes linearlow density polyethylene, low density polyethylene, ethylene copolymer,or a combination thereof.
 15. The packaging film of claim 13, whereinthe nanoclay constitutes from about 0.1 wt. % to about 15 wt. % of thepolymer composition.
 16. The packaging film of claim 1, wherein the corelayer contains the polymer composition.
 17. The packaging film of claim16, wherein the ethylene polymer includes high density polyethylene. 18.The packaging film of claim 16, wherein the nanoclay constitutes fromabout 0.5 wt. % to about 20 wt. % of the polymer composition.
 19. Thepackaging film of claim 16, wherein the polymer composition include ablend of low density polyethylene, linear low density polyethylene, anda high density polyethylene.
 20. The packaging film of claim 16, whereinhigh density polyethylene constitutes from about 10 wt. % to about 85wt. % of the polymer composition.
 21. The packaging film of claim 1,wherein the film is a blown film.
 22. The packaging film of claim 1,wherein the film is a cast film.
 23. The film of claim 1, wherein thefilm exhibits a normalized noise level of about 2.5 or less asdetermined at a frequency of 4,000 Hz, wherein the normalized noiselevel is determined by dividing the noise level of the film by the noiselevel of an ambient environment.
 24. The film of claim 1, wherein thefilm exhibits an oxygen transmission rate of about 350 cm³/in²*24-hoursor less.